Internal shorting fuse for a high-intensity discharge lamp

• US 4,205,258 A
• Filed: 03/21/1979
• Issued: 05/27/1980
• Est. Priority Date: 03/21/1979
• Status: Expired due to Term

• Current Assignee: Philips Electronicsnorth America Corporation (Koninklijke Philips N.V.)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Ward, Patrick C.
• Primary Examiner(s): Smith, Alfred E.
• Assistant Examiner(s): Roberts, Charles F.
• Application Number:
  US06/022,404
• Time in Patent Office: 433 Days
• Field of Search: 315/73, 315/74, 315/75
• US Class Current: 315/73
• CPC Class Codes: H01J 61/56 One or more circuit elements structurally associated with the lamp

Abstract

A high-intensity discharge lamp having an arc tube which is enclosed by and supported within a light-transmitting outer envelope which is spaced from the arc tube. The outer envelope enclosing a hard vacuum. Electrical lead-in means are sealed through the arc tube connected to the electrodes. Electrical adapter means are affixed to the outer surface of the protective envelope to facilitate electrical connection for the lamp to a source of electrical power. A pair of electrical conductors electrically connect the electrical adapter means to the electrical lead-in means. Fuse means is provided. The fuse means has a fusible element extending from one of the electrical conductors and separated from and encircling an insulating sleeve means carried about the other of the electrical conductors, so that the spacing therebetween constitutes the shortest gap within the envelope between opposite current-carrying components. The hard vacuum enclosed by the outer envelope is obtained by flashing barium getter means.

Improved insulating sleeve means is provided having an outer hollow elongated sleeve member having insulating spacing means integral therewith and projecting inwardly from the inner surface thereof and positioned a predetermined distance inwardly from the ends of the sleeve member. The insulating spacing means is provided with a bore to receive and encircle the other electrical conductor in electrically insulative relationship to prevent the outer elongated sleeve member from contacting the other electrical conductor, whereby barium flashed during gettering that may be adhered to the surface of the outer hollow sleeve member is prevented from causing an electrical short of the arc tube.

Claims

1. In combination with a high-intensity discharge lamp comprising an arc tube which is enclosed by and supported within a light-transmitting outer envelope which is spaced from said arc tube, said outer envelope enclosing a hard vacuum, said arc tube enclosing a discharge-sustaining filling and having electrodes operatively positioned therein proximate the ends thereof, electrical lead-in means sealed through said arc tube and connected to said electrodes, electrical adapter means affixed to the outer surface of said protective envelope to facilitate electrical connection of said lamp to a source of electrical power, a pair of electrical conductors electrically connecting said electrical adapter means to said electrical lead-in means, fuse means comprising a fusible element extending from one of said electrical conductors and separated from and encircling an insulating sleeve means carried about the other of said electrical conductors with the spacing between said fusible element and the other of said electrical conductors as determined by said insulating sleeve means constituting the shortest gap within said envelope between opposite current-carrying components so that any arc occurring between said current-carrying components will occur proximate said insulating sleeve means and melt said insulating sleeve means and fuse said fusible element to said other electrical conductor and thus render said lamp inoperative, and the hard vacuum enclosed by said outer envelope having been obtained by flashing barium getter means, the improvement which comprises:

an improved insulating sleeve means separating said fusible element from the other of said electrical conductors, said improved insulating sleeve means comprising an outer hollow elongated sleeve member, said outer hollow elongated sleeve member about which said encircling fusible element is wrapped, said outer hollow elongated sleeve member having insulating spacing means integral therewith and projecting inwardly from the inner surface thereof and positioned a predetermined distance inwardly from the ends of said outer sleeve member, said insulating spacing means provided with a bore to receive and encircle said other electrical conductor in electrically insulative relationship to prevent said outer hollow elongated sleeve member from contacting said other electrical conductor, whereby barium flashed during gettering that may be adhered to the surface of said outer sleeve member is prevented from causing an electrical short of said arc tube.

2. The lamp of claim 1, wherein said improved insulating sleeve means is made of glass.

3. The lamp of claim 1, wherein said insulating spacing means is positioned at least 1 millimeter inwardly from the ends of said outer sleeve member.

4. In combination with a high-intensity discharge lamp comprising an arc tube which is enclosed by and supported within a light-transmitting outer envelope which is spaced from said arc tube, said outer envelope enclosing a hard vacuum, said arc tube enclosing a discharge-sustaining filling and having electrodes operatively positioned therein proximate the ends thereof, electrical lead-in means sealed through said arc tube and connected to said electrodes, electrical adapter means affixed to the outer surface of said protective envelope to facilitate electrical connection of said lamp to a source of electrical power, a pair of electrical conductors electrically connecting said electrical adapter means to said electrical lead-in means, fuse means comprising a fusible element extending from one of said electrical conductors and separated from and encircling an insulating sleeve means carried about the other of said electrical conductors with the spacing between said fusible element and the other of said electrical conductors as determined by said insulating sleeve means constituting the shortest gap within said envelope between opposite current-carrying components so that any arc occurring between said current-carrying components will occur proximate said insulating sleeve means and melt said insulating sleeve means and fuse said fusible element to said other electrical conductor and thus render said lamp inoperative, and the hard vacuum, etc., components, and the hard vacuum enclosed by said outer envelope having been obtained by flashing barium getter means, the improvement which comprises:

an improved insulating means separating said fusible element from the other of said electrical conductors, said insulating means comprising an outer hollow elongated sleeve member and an inner hollow elongated sleeve member positioned a predetermined distance inwardly from the ends of said outer sleeve member, said outer sleeve member about which said encircling fusible element is wrapped, said inner sleeve member provided with a bore to receive and encircle said other electrical conductor in electrically insulative relationship to prevent said outer hollow elongated sleeve member from contacting said other electrical conductor, whereby barium flashed during gettering that may be adhered to the surface of said outer elongated sleeve member is prevented from causing an electrical short of said arc tube.

5. The lamp of claim 4, wherein said improved insulating sleeve means is made of glass.

6. The lamp of claim 4, wherein said inner hollow elongated sleeve member is positioned at least 1 millimeter inwardly from the ends of said outer sleeve member.